Question 474174
  <pre><font face = "Tohoma" size = 4 color = "indigo"><b> 
Hi,
Let x represent # of years ago that Zhongmin was three times as old as Mingyong
Question states***Zhongmin is 50 years old. His son, Mingyong is 24 years old
  50-x = 3(24-x)
   2x = 22
    x = 11yr,  # of years ago that Zhongmin was three times as old as Mingyong
CHECKING our Answer***
 (50-11) = 39 = 3*(24-11) = 39